There are large amounts of various underground resources such as natural gas and oil under the deep sea. Various offshore constructions have been developed to mine those underground resources and various efforts have been made to mine resources under the deep sea under an extreme environment.
Various offshore constructions working on the sea, including ships, require a mooring apparatus for maintaining their positions against external force such as waves, wind, and currents. A turret that can turn around a predetermined position to make it possible to load and process underground resources even if offshore constructions are moved by waves, wind, or currents is generally used for those mooring apparatuses. The turret is a device that is combined directly with offshore constructions such as a ship or connected to offshore constructions through a hawser on the sea and keeps the offshore constructions at a position.
The turret maintains its position on the sea, using a plurality of mooring chains connected to the bottom of the sea. However, large tension is exerted in mooring chains extending to the deep sea, so it is difficult to connect them to a turret.
Further, the positions of mooring chains connected to a turret have a large influence on the stability of the turret, so there is a need for a turret that can be easily installed and stably floated on the sea.
Korean Patent Application Publications No. 10-2010-0124733 (2010 Nov. 29) discloses an example turret and a floating supporting fitted with the turret according to a conventional art.